Skip to 0 minutes and 20 secondsSPEAKER: Hello and welcome to this first lecture giving an overview on what is known about the new coronavirus named SARS-CoV-2 which causes the disease named COVID-19, where the virus comes from, and how it spreads, and how COVID-19 compares to diseases caused by other coronaviruses and how we measure severity of these diseases. So what is a coronavirus? Coronavirus are a large family of viruses. They get their name from the crown-like spikes that can be seen on their surface with electron microscopy. They were first identified in the middle of the 1960s and they can cause very mild symptoms like a common cold, or in some cases, they can cause severe disease.
Skip to 1 minute and 9 secondsThere are many coronaviruses circulating in animals and some that are circulating in humans. Rarely, one of the viruses infecting animals may evolve to infect humans and spread between them. The virus causing the disease Severe Acute Respiratory Syndrome, or SARS, in 2002 was associated with civet cats. And the virus causing Middle Eastern Respiratory Syndrome, MERS, in 2012 was associated with dromedary camels. These viruses didn't always, but could, cause severe disease in humans. The new type of coronavirus causes COVID-19 and cases were first reported in Wuhan, a city with a population of around 11 million and the capital of Hubei Province, China, in December 2019.
Skip to 1 minute and 59 secondsMany early cases were associated with the Huanan Seafood Wholesale Market, but whether this was the site of the emergence is not yet clear. It is also not yet clear which animal the new coronavirus is associated with, although there have been data suggesting it is similar to those found in some bats. Coronaviruses affect the airways, the breathing passages, or respiratory tract. Symptoms can be mild like the common cold, including a runny nose and cough. However, symptoms can be more severe and can cause, for example, difficulty in breathing. Severe illness was seen not infrequently in cases of MERS and SARS. So far, we know that not everyone infected with the virus causing COVID-19 has symptoms.
Skip to 2 minutes and 46 secondsCommon symptoms are fever, cough, and feeling tired. Some people become seriously ill. And data are limited at present, but this seems to be more likely in those who are elderly and/or who have other health problems. Case fatality risk or rate is a measure of how serious a disease is as it tells you the proportion of people who die from the disease out of those who have it. For MERS, the case fatality was high as over a third of cases died. In SARS, it was lower with one in 10 people dying. At present, for COVID-19 it is around 2%, which is 1 in 50 people with the disease dying. Respiratory viruses are usually transmitted through either droplets, aerosols, or contact.
Skip to 3 minutes and 34 secondsDroplets are larger particles that travel less than a metre. Smaller particles can form aerosols and may travel further. Contact is usually from droplets landing on objects which are then touched by another person who then touches their eyes, nose, or mouth. The main way the virus causing COVID-19 seems to spread is via droplets, for example, when someone coughs or through contact with droplets on another object if the eyes, nose, or mouth are then touched. Potential for transmission by aerosol, the smaller particles, is under investigation. How a virus spreads informs the measures to prevent it. So to prevent droplet or contact transmission washing hands, maintaining distance from those coughing or sneezing, not touching your hands or mouth can all help prevent infection.
Skip to 4 minutes and 26 secondsAdvice from health care, national, or local authorities and employers should be followed.
Overview of the coronavirus and COVID-19
In this mini-lecture, Dr Anna Seale describes what is known about the new coronavirus, including where it came from and how it spreads (recorded 2nd March 2020).
Intended learning outcomes
- Describe what is known about the new coronavirus (SARs-CoV-2)
- Where the virus came from and how it spreads
- How COVID-19 compares to diseases caused by other coronaviruses
- How we measure severity of disease
© London School of Hygiene & Tropical Medicine 2020